ClassCastException

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hon123456 - 17 Jan 2006 05:34 GMT

Dear all,
I am trying to learn Java. I found the explanation of
ClassCastException in Sun website as follows. But it seems rather
simple. I don't understand " cast an object to a subclass of which it
is not an instance" in the explanation. Please help me. By the way,
please suggest any good website that explains the ClassCastException in

detail.

>From sun:

Thrown to indicate that the code has attempted to cast an object to a
subclass of which it is not an instance. For example, the following
code generates a ClassCastException:

Object x = new Integer(0);
System.out.println((String)x);

Thanks.

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Aj-India - 17 Jan 2006 07:10 GMT

try this...

System.out.println(x.toString());

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Thomas Weidenfeller - 17 Jan 2006 07:49 GMT

> I am trying to learn Java. I found the explanation of
> ClassCastException in Sun website as follows. But it seems rather
> simple.

Yes it is.

> I don't understand " cast an object to a subclass of which it
> is not an instance" in the explanation.

There is nothing more to say. Do you know what an object is? Do you know
what a subclass is? Do you know what an instance is? If not, get a good
beginners textbook and start to read. Look for the section close to the
start of the book where they talk about objects and types.

> Please help me. By the way,
> please suggest any good website that explains the ClassCastException in
> detail.

A web site explaining class cast exceptions? You are making an affair
out of something which is nothing.

> Object x = new Integer(0);
> System.out.println((String)x);

An Integer is not a String. Please, get a textbook.

/Thomas

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The comp.lang.java.gui FAQ:
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http://www.uni-giessen.de/faq/archiv/computer-lang.java.gui.faq/

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dp_ganatra@rediffmail.com - 17 Jan 2006 11:53 GMT

Hi,

This exception is thrown when attempting to cast an object to a class
that it cannot be cast to.

Class cast exception is thrown when an attempt is made to cast an
object which is not of the appropriate runtime type. If u see the
class hierarchy, it will look like ...

java.lang.object
java.lang.Throwable
java.lang.Exception
java.lang.RuntimeException
java.lang.ClassCastException

You can also visit :
http://www.cs.duke.edu/csed/ap/subset/doc/ap/java/lang/ClassCastException.html

You can visit

> Dear all,
> I am trying to learn Java. I found the explanation of
[quoted text clipped - 15 lines]
>
> Thanks.

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ClassCastException

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